Acetyl choline acetate



Patented Sept. 3, 1935 ACETYL CHOLINE ACETATE Jcseph K. Cline, Woodbridge, N. 3., assignor to Merck & Co., Inc., Eahway, N. 3., a corporation of New Jersey No Drawing. Original application March 30,

1931, Serial No. 526,549. Divided and this application February 8, 1934, Serial No. 710,329

1 Claim. (Cl. 26025) This is a division of my application, Serial No. and produce preparations of a satisfactory degree 526,549, filed March 39, 1931, for Process for preof purity. paring certain acyl-cholinc esters, etc. issued on The old methods used for producing acetyl May 8, 1934 as Patent No. 1,957,443. choline compounds followed reactions under con- 6 This invention relates to improved processes ditions which either did not readily lend themfor the production of salts of aliphatic acid esters selves to satisfactory isolation, or were not of the of choline. In general such processes are conbest efficiency as to yield and simplicity. cerned with the esterification (or acylation) of Baeyer (supra), in 1867, and Nothnagel various choline salts with aliphatic acid anhy- (supra) in 1894, carried on their experiments for 10 drides. the production of the chloride by acetylating 1'0- Choline and its esters, and more especially choline chloride with acetyl chloride; Fourneau acetyl-choline and its salts, have achieved conand Page (supra), in 1914, reacted upon trisiderable pharmacological importance in recent methylamine with chloro-ethyl acetate; While y but n Spite Of the la ge amount of work Abderhalden and Pa-ffrath (supra) (1925) re- I which has been done with choline compounds, ported the formation of acetyl-choline by the 15 y h v n f d h xt nsiv appl i n action of sodium acetate on choline in the presin human py Which might be eXDeCted from ence of an enzyme. But none of these investithe therapeutic possibilities indicated y the gators succeeded in isolating the compound or in pharm i l i Thi i e to h f determining its actual physical and chemical 0 that these preparations have not been in a form roperties, Hunt (supra), in 1915, and thereand in Such 3 Con purity Which Would after, studied pharmacologically the physiologimeke em d y v ab e d adaptable for cal action of solutions containing choline and its such use. compounds, and reported that he had succeeded he meet interesting cempeunds 0f the Series in forming acetyl-choline chloride in such solupp to be the Salts of acetyl Cheline, Since tions. It also does not appear, however, that he 25- the general indications are that t would be at any time succeeded in isolating and defining likely to be the most active forms for therapeutic th pure b t nce emp m Th pr i n f c l ChoIine, Jones and Major (supra), in 1930, succeeded in ts Sa and p lly acetyl ch Chloride, isolating acetyl choline chloride in the form of a have been the subject of study for many years, pure salt, and were thus enabled, for the first 30' but it pp s that not until recently have they time, definitely to determine its physical and been ge y isolated in the form 0f pure and chemical properties. They produced the salt in defi y identified entitiesthe form of a white hygroscopic crystalline pow- I am familiar with the work of Baeyer (Ann. der t melting point f 51 Q My t 142,325 (1867)), Nothnagel (Arch. Pharm. gations have onfirmed these finding and 1 35 232,265 (1894)), F u eau and Page (131111- have now found also that I can reproduce this Ch m. (1914:) Abdel'halden and salt, in the same form, by my new process herein Paffrath (Fermentforschung 8,299 (1925); C. A. djsclosed 2532 and Hu h 7, 306, While it appears, from what has been said, that 40 (1915)), as well as the more r c t investigea number of chemists acylated choline and its 40 tions of Jones and Major (Jr. Amer. Chem. Soc. Simple Salts, none of t Seems t have 52, 307 (1930)) in this field. S0 far a I av ceeded in isolating pure esters of such salts of be n ab e to ea y a udy f he literature, choline from the products of their reactions, even the latter were the first to Succeed i iso at g though it appears that several investigators did the pure acetyl-choline chloride and iodide and succeed in isolating and defining some of the 45 to study and describe their physical and chemidouble salts, e. g., chloro platinites and aurichlocal properties. I am also familiar with new rides, which, however, are presumably not of processes developed by Jones and Major for especial medicinal interest in the present state making their salts. of our knowledge. Thus Baeyer (supra) and At the suggestion of Randolph T. Major, I unlater Nothnagel (supra) were unable to isolate dertook the task of developing further improved pure acetyl choline chloride from the product processes for the production of such aliphatic that they obtained by the action of acetyl chloesters of choline and salts, and have now been ride on choline chloride. Hunt (supra) did not successful in working out processes which are isolate pure acetyl choline from the product of 5 relatively technically simple, render good yields, the interaction of choline and acetyl chloride, nor

did Abderhalden and Pafirath obtain pure acetyl choline by the action of sodium acetate on choline in the presence of an enzyme. Contrary to the general assumption, I have now found that I can obtain pure acyl-choline salts by the action of acyl anhydrides on choline salts, according to the equation:

By way of illustration I set forth in the following examples the preferred forms of the process which can also readily be followed in the production of other analogous esters and salts, by appropriate adaptation.

Example I .Acetyl choline chloride.0ne part of choline chloride is treated with five parts of acetic anhydride. The mixture is heated at C. in a closed vessel for about one hour in excess of the time required for complete solution. The vessel is then cooled, and the formed acetylcholine chloride is precipitated by means of the addition of anhydrous ether. The precipitate is filtered off and dried. Thereafter the precipitated mass is purified by dissolving it in absolute alcohol and reprecipitating with dry ether. The formed mass is then filtered off, and washed with anhydrous ether. The final product is obtained in the form of white crystals melting at 14.9-

Example II .Propionyl-choline chloride-One part of choline chloride is treated with three parts propionic anhydride. The mixture is heated at 100 C. for about one hour in excess of the time required for complete solution. The vessel is then cooled and the formed propionyl choline chloride is precipitated by means of the addition of anhydrous ether. The precipitate is filtered and dried. Thereafter the precipitated mass is purified by dissolving it in absolute alcohol filtering if necessary and reprecipitating with dry ether. The formed mass is then filtered off and washed with anhydrous ether. The final product appears as crystals, soluble in alcohol, insoluble in ether, melting at C.

Example III.--Butyryl-choline chloride.--One part of choline chloride is treated with four parts butyric anhydride. The mixture is heated at 100 C. in a closed vessel for about one hour in excess of the time required for complete solution or about five hours. The vessel is then cooled and the formed butyryl choline chloride is precipitated by means of the addition of anhydrous ether. The precipitate is filtered off and dried. Thereafter the precipitated mass is purified by dissolving it in absolute alcohol, filtering if necessary and reprecipitating with dry ether. The final product is obtained in the form of crystals.

Eosample IV.Acetyl-choline acetate.0ne part of choline acetate is treated with five parts of acetic anhydride. The mixture is heated at 100 C. in a closed vessel for about one hour in excess of the time required for complete solution, or a total of about two hours. The vessel is then cooled and the formed acetyl choline acetate is precipitated by means of the addition of anhydrous ether. The precipitate is filtered off and dried. Thereafter the precipitated mass is purified by dissolving in absolute alcohol filtering if necessary and reprecipitating with dry ether. The formed mass is then filtered off and washed with anhydrous ether. The final product is obtained in the form of crystals melting at MKS-148 C.

As will be readily understood, the process may be varied somewhat within reasonable limits as to the actual relative quantities of the materials employed, temperature, etc., without departing from the spirit and scope of the invention disclosed.

It will thus be seen that by this process it is possible to produce a wide range of acyl-choline salts by simply treating the appropriate salts with a given aliphatic acid anhydride, in the manner described. Thus a variety of salts of choline esters suitable for medicinal use which have not hitherto been produced, and which will considerably extend the armamentarium of the physician with respect to class of remedial agents which are now assuming an important role in therapy.

Having thus set forth my invention, I request the allowance of the following claim:

As a new medicinal preparation, acetyl-choline acetate in the form of a white crystalline powder, soluble in alcohol, insoluble in ether, with a melting point of 148-149 C., and having the formula:

(CH3) 3N(OOCCH3) C2H4 OOCCH3.

JOSEPH K. CLINE. 

